Depression is a common mental disorder that threatens millions of people over the world. A deficit of the neurotransmitter serotonin in the central nervous system (CNS) is thought to be an important physiological factor for depression. 5-Hydroxytryptophan (5-HTP) is the direct biosynthetic precursor to serotonin in humans and animals. It has been shown to be clinically effective in treating depression with relatively few side effects. In most European countries, 5-HTP is a commonly prescribed drug for multiple treatment purposes; while in North America market it is sold as an “over-the-counter” dietary supplement.
In addition to depression, 5-HTP has been shown to be effective in treating insomnia, fibromyalgia, obesity, cerebellar ataxia, chronic headaches, etc. (Birdsall, Altern. Med. Rev. 1998; 3(4):271-280), as evidenced by studies conducted in the past two decades indicating that 5-HTP may have positive effects in the treatment of disorders such as fibromyalgia (Caruso et al., J Int Med Res. 1990; 18:201-209; Puttini et al., J Int Med Res. 1992; 20:182-189), insomnia (Attele et al., Altern Med Rev. 2000; 5(3):249-259), migraines and headaches (Ribeiro, 2000 June; 40(6):451-6), eating disorders such as polyphagia (Cangiano et al., Int J Obes Relat Metab Disord. 1998; 22:648-654; Ceci et al., J Neural Transm. 1989; 76:109-117) as an aid in the management of obesity and diabetes, and hot flashes (Curcio et al., Altem Med Rev. 2005; 10(3):216-21; Freedman, Maturitas. 2010 April; 65(4):383-5).
5-HTP is also considered as a potential feed additive for farm animals, as either a preventative of, or therapeutic agent against, mastitis in cattle (Jury et al., PLoS One. 2015 Feb. 17; 10(2):e0117339; Pai et al., Biomed Res Int. 2015; 2015:364746; Horseman et al., Annu Rev Anim Biosci. 2014 Feb. 2: 353-74), and in the regulation of lactation function in mammals (Marshall et al., J Mammary Gland Biol Neoplasia. 2014 March; 19(1):139-46; Collier et al., Domest Anim Endocrinol. 2012 August; 43(2):161-70; Hemandez et al., J Endocrinol. 2009 October; 203(1):123-31), thus having great potential to increase milk production by said animals. In certain avians (e.g., chickens) 5-HTP appears to be associated with the regulation of circadian cycle (Thomas et al., Cell. Mol. Neurobiol. 1991, 11(5):511-527) and other positive health effects (Moneva et al., Bulgarian J. Ag Sci. 2008 14(4):424-431) with positive impact in the animal growth and productivity.
Currently, 5-HTP is produced through extraction from the seeds of Griffonia simplicifolia, a woody climbing shrub grown in Africa. The season- and region-dependent supply of the raw materials has limited its cost-effective production and broad clinical applications. In addition, Griffonia derived 5-HTP has been contaminated with a compound called Peak X, leading the USDA to briefly remove the supplement from shelves in the US.
The current bulk wholesale price for 5-HTP ranges from 400 to 1000 USD/kg. Despite the current high production cost and limited supply, the global market of 5-HTP is still about 120,000 kg (bulk value 50-100 million dollars) with an annual growth rate of about 7%. The 5-HTP end products are even more expensive, and the retail market values of the end products are much higher.
In 2012, North America represented about 48% of the market followed by Europe and Asia Pacific with the major market segment being human nutritional supplement. Emerging market segments (e.g., animal nutrition, human therapeutic co-adjuvant) are likely to grow at rates much higher than those predicted for the over-the-counter human nutritional supplement.